An example of an optical disk on which an image can be formed is disclosed in JP-A-2002-203321. The optical disk is configured such that a dye layer (recording layer), a reflection layer, a visible light characteristic changing layer, and a protective layer are successively formed on one side of a transparent substrate. It is possible to visually identify the visible light characteristic changing layer through the transparent protective layer. The visible light characteristic changing layer is a layer made of a material changing in visible light characteristics of the irradiated site when irradiated with a laser light of a prescribed power through the protective layer.
Recording of data is carried out by applying a writing laser from an optical pickup from the substrate side, and thermally changing the characteristic of the dye layer (recording layer).
In order to draw characters, patterns, and the like on the label side of an optical disk, the following procedure is carried out. When the optical disk is set on a turn table of a write unit, it is set with the label side of the optical disk facing the side to be irradiated with a laser beam. Namely, it is set on the turn table upside down from the state of general data recording. Thus, a laser beam from the optical pickup is applied to the visible light characteristic changing layer through the protective layer of the optical disk. The laser beam is concentrated through an objective lens of the optical pickup, so that the energy density is increased, resulting in an increase in temperature of the visible light characteristic changing layer. As a result, the visible light characteristic of the part irradiated with the laser beam, such as the transmittance of the visible light changes. The image on the label side is expressed by the contrast between before change and after change of the visible light characteristics of the visible light characteristic changing layer.
As the document for drawing characters and the like on the label side of an optical disk by a laser beam, there is the following one:    Patent Document 1: JP-A-2002-203321